On Wed, 3 Mar 2010, Bruno Randolf wrote: > i agree with what you said. > > let's not forget the bigger picture: while it's good to make TSF reads as > reliable as possible, we can never be 100% sure about the TSF anyways (and the > extended RX timestamps therefore, which use the current TSF and 15bit from the > descriptor) as long as HW merges can update the TSF any time. so with ath5k > hardware there will always be some uncertainity
>(can we say that ath5k hardware is crap for IBSS?). No - one cannot prove that ath5k hardware is crap in IBSS until you can demonstrably show that all parts of the driver are correct. Stating the ath5k hardware is crap in IBSS is done by developers who have bugs in their code (and cannot find the bugs). > > but right now the TSF is used for IBSS merging, beacon timer configuration and > radiotap headers only. forget about the headers, so the only thing we need to > be concerned is beacon timers and IBSS merging. yes, but you do need to correctly read the TSF. I did a test (admitedly with madwifi, but the results may hold) that if the calculated tbtt time is wrong (too large or too small) then that particular node never sends out beacons, and so merging is "problematic" - have you done a test with ath5k where the calculated tbtt value is wrong - what happens? At the very least, you will have out of sync beacons - where one node sends beacon at the wrong part of the beacon interval (which hurts throughput). > if mac80211 is smart enough, a few extra merges to the same BSSID > shouldn't hurt too much. also there is already some code in place to > check for TSF jumps and fix beacon timer configuration, not sure if > that's enough, but it already helps to keep track of jumping TSF values. Are you suggesting that we have to go through the entire IBSS code and consider the result of bogus TSF values in there? There is a quote on the wall here from a colleague. How do you make it work ??? oh, the usual, get everything right. Derek. -- Derek Smithies Ph.D. IndraNet Technologies Ltd. ph +64 3 365 6485 Web: http://www.indranet-technologies.com/ "The only thing IE should be used for is to download Fire Fox" "My favorite language is call STAR. It's extremely concise. It has exactly one verb '*', which does exactly what I want at the moment." --Larry Wall _______________________________________________ ath5k-devel mailing list ath5k-devel@lists.ath5k.org https://lists.ath5k.org/mailman/listinfo/ath5k-devel
